which line you choose to line up with; inside of line, outside of line really does not matter as much as consistancy! if you choose to line up with the outside edge of the line then everytime you cut you should do it that way. the reason you are having problems is because you are not being consistant. once you decide how you are going to always do it then you need to measure the actual cut piece and determine if doing it that way means you use a scant 1/4" or a regular 1/4" consistancy is the key :)